"Gemini" is the eleventh episode of the eighth season of Stargate SG-1.


SG-1 is shocked to see a duplicate of Lt. Colonel Samantha Carter, who reveals that she is a Replicator created by Fifth. She wishes to be destroyed with the Replicator disruptor, to prevent Fifth from getting his hands on her again, since he is heading straight for the Milky Way. However, the Tau'ri plan to have her help them defeat them, since she claims Fifth has created a cipher to become immune to the disruptor.

Previously on Stargate SG-1[]

SG-1 encounter a group of Human-form Replicators on the planet Hala. They managed to trap them in a Time dilation field by betraying the trust of Fifth. A year later, Major Samantha Carter is beamed to a Replicator ship and tortured by Fifth before being rescued by SG-1. Fifth then uses the knowledge and information he gained during Carter's imprisonment to create a Human-Form Replicator who is later shown to be a copy of Carter known as Replicator Carter.


Gemini 1

Daniel and Sam walking through the Base.

Lt. Colonel Samantha Carter and Dr. Daniel Jackson walk through a level of the SGC, discussing the Prometheus' new assignment which is to go to find the lost Atlantis expedition. Jackson wants to go but Carter reveals that Brigadier General Jack O'Neill has turned down Jackson's request yet again with Carter quoting that O'Neill's exact words were "Over my dead body".

As soon as Jackson has gone into the elevator, Stargate Command receives an unscheduled off world activation, and with it an old IDC that had been used by Carter. Then comes the message, "SEND M.A.L.P.," and when one is sent through, it reveals a second Carter. She identifies herself as a Human-form Replicator, designed by Fifth with all of Carter's memories and thoughts. Her message is urgent: Fifth has discovered a way to overcome the Replicator disruptor O'Neill designed while he had the Ancient Repository of knowledge downloaded into his brain. The replicator version of Carter has rebelled against Fifth and offers her assistance in altering the weapon to work again.

Replicator Carter 4

Replicator Carter arriving at the Alpha Site.

Carter accepts the proposal, and with O'Neill's approval, goes to the Alpha Site with Teal'c to work on the weapon with Replicator Carter herself soon arriving.


Replicator Carter probing the original Carter's mind.

To get an insight into what happened, Replicator Carter reluctantly probes the real Carter's mind, showing Carter one such training scenario of Replicator Carter arriving at the SGC before killing her original self's colleagues and friends in cold blood which left Replicator Carter in tears.

After connecting to the Replicator collective, Replicator Carter downloaded the cipher and after experimenting with the disruptor, they adjust the weapon and launch a Replicator disruptor satellite.

However, it is eventually revealed that Fifth had no immunity to the weapon, and in fact he had sent her to study the weapon and develop the very cipher she claimed to be trying to defeat. She destroys Fifth with the disruptor satellite that had worked all along and makes her way to the Stargate.

After taking out the guards, she begins dialing the Stargate. Teal'c attempts to stop her but she deactivates the nanites in her own left arm Teal'c is holding and she escapes through the Stargate while the arm itself dissolves into nanites.

Later, in the lab, Jack and Teal'c try to assure Carter that what happened wasn't her fault but Carter grimly remarks that it is her fault, because Replicator Carter learned betrayal from Fifth who had in turn learned it from the original Carter herself.


Appearances for Gemini





Sentient Species



Notable quotes[]

O'Neill: Alright, you got our attention. Who are you?
Replicator Carter: My name is Samantha Carter.
O'Neill: Alright. We've got a little conflict with that statement. We've already got one here.
Replicator Carter: There are two of us.
O'Neill: If only.

Replicator Carter: I was made in Samantha Carter's image. I know what she knows. Feel what she feels.
Carter: You were made. Who made you?
Replicator Carter: The one you call Fifth.
Carter: Oh my god. She's a replicator.

Carter: ...and we need the Asgard to send us a disruptor satellite as soon as possible.
O'Neill: I've already talked to 'em. Be there in there in 30 minutes, or it's free.

O'Neill: I need you to be perfectly honest with me. Is Carter letting herself get too involved in this one?
Teal'c: Colonel Carter and the replicator share thoughts and memories. It is understandable that a certain sympathy would develop between them.
O'Neill: Can’t have that.
Teal'c: However I do not believe Colonel Carter would allow these feelings to interfere with the commission of her duties.
O'Neill: Fair enough. But when the time comes, I want you to finish the job.
Teal'c: Understood.

Fifth: Why?
Replicator Carter: You should know. You made me what I am.

Carter: We will stop you.
Replicator Carter: You're forgetting, I know exactly how your mind works. I know what you're going to do before you even think of it.

(Carter is working on Replicator Carter's nanites)
O'Neill: You know, I'm still of a strong belief that it's a bad idea to have that stuff on the base.
Carter: She deactivated these cells when she separated them from her arm.
Teal'c: Can we be certain they will not become active again?
Carter: She deliberately shut down the cohesive energy between them so it would be more difficult for me to figure out how she made herself immune to the disrupter.
O'Neill: Now, how do you know that?
Carter: Because that's what I would have done.
O'Neill: Carter…
Carter: Sir, if you don't mind, I've got a lot of work to do. We've never had the opportunity to study human-form Replicator cells before. If we can learn something from them, this won't be a total loss.
O'Neill: This isn't your fault.
Carter: I'm not so sure about that. Fifth came here because of me. She rejected him because she was made like me. Now we've got Replicators in our galaxy and they're immune to the only technology we have that could have stopped them.
Teal'c: None of us correctly anticipated the actions of the Replicator.
Carter: I thought she was afraid of him. But really she just wanted to get rid of him so she could lead the Replicators herself. She killed him because she thought he was weak.
O'Neill: Carter, she isn't you.
Teal'c: O'Neill is correct. Though she shared your memories, her personality was altered.
Carter: The fact is, she learned betrayal from Fifth. And he learned it from me.


Main Characters

Guest Stars


  • "Gemini" is Latin for "twins." It is also the name of a constellation depicting the mythical twin brothers Castor and Pollux. (For female twins, the proper word would be geminae.)
  • The Alpha Site on P4X-650 is located on the planet's equator as they were able to put the Replicator Disruptor satellite in a stationary orbit above the base which is only possible for equatorial orbits. The altitude given by Thor also means that P4X-650 is less massive than Earth.
  • In reference to a Replicator disruptor satellite that was requested from the Asgard to protect the Alpha Site from a potential Replicator attack, Brigadier General Jack O'Neill states, "Be there in thirty minutes, or it's free." This is a cultural reference to pizza delivery places in the U.S. which promise delivery within thirty minutes of the order, or it's free.
  • Broadcast in the USA as the 11th episode of the season, it is the 12th on Region 2 DVDs.
  • Dr. Daniel Jackson only appears briefly in this episode. It's often presumed that this episode takes place at about the same time as the next episode, "Prometheus Unbound". When Jackson enters the elevator after talking to Lt. Colonel Samantha Carter, he went to try to convince O'Neill to allow him to join the crew of the Prometheus on their mission to Atlantis which is shown on the teaser for "Prometheus Unbound". He later appears in a vision that Replicator Carter shows Carter, where the replicator comes through the Stargate and shoots Jackson and MSgt. Sylvester Siler.
  • This episode takes place approximately four months after the events of "New Order, Part 2".
  • In the illusion allegedly created by Fifth, O'Neill's uniform does not have general stars. This is consistent with the fact that the Replicator Carter was not then aware that he had been promoted to Brigadier General as Carter's memories were copied shortly before the promotion took place.
  • The way Fifth and Replicator Carter communicate is similar to the one used in the TV series Earth 2.


  • There was no indication where the connection was originating from, so Stargate Command had no way of knowing where to "Send the M.A.L.P."
  • When the gate is dialed it can be observed, when the last chevrons is activated, that the prop bends slightly.
  • Replicator Carter claims to be able to upload data directly into the base's mainframe, and then moves her hand into a computer monitor, presumably to allow her nanites to interface directly with the computer. This does not make sense considering that monitors only display output from a computer and are not capable of inputting data into a computer. Later in the episode she interfaces with a computer by moving her hand into a keyboard, which makes considerably more sense, since keyboards are input devices and so interfacing with it would allow her to interact with the computer.
  • Thor tells Teal'c that the Disruptor satellite should be placed in geosynchronous orbit above the alpha site base with an inclination of 0 and a specific altitude. This would actually require a stationary orbit (which is a special case of a synchronous orbit where the orbiting body remains above a specific point rather than just passing over a specific point at the same time every sidereal day) and there is only one possible inclination and altitude such a satellite could be placed at for a given body. Also, the prefix "Geo-" is only used if the orbit is around Earth. Around any other body, the "Geo-" is dropped or replaced with another appropriate prefix.
  • Teal'c should not have struggled to pull Replicator Carter back from the Stargate. Once she passed beyond the event horizon, she would have been converted to energy and lacked physicality, thus preventing her from exerting force of any kind. In addition, he could've held her in place until the wormhole reached its maximum time limit and disconnected, leaving Replicator Carter as little more than a forearm.
  • When Replicator Carter shuts down power on the base, one of the airmen comments that the dialing computer is offline, while standing next to the Dial Home Device, which normally requires absolutely no external computer input.

Other languages[]

  • French: Vulnérable (Vulnerable)
  • Italian: Gemelle (Twin)
  • Spanish: Géminis (Gemini)
  • Czech: Blíženci (Gemini)
  • German: Gemini (dubbed in English)
  • Hungarian: Ikrek (Gemini)

Links and navigation[]

Smallwikipedialogo This page uses content from Wikipedia. The original article was at Gemini (Stargate SG-1). The list of authors can be seen in the page history. As with SGCommand, the text of Wikipedia is available under the GNU Free Documentation License.
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